DISCHARGE AMOUNT MEASURING DEVICE AND METHOD FOR ROTATIONAL ELECTRIC MACHINE

• US 20100271002A1
• Filed: 04/27/2010
• Published: 10/28/2010
• Est. Priority Date: 04/27/2009
• Status: Active Grant

• Current Assignee: DENSO Corporation, Nippon Soken, Inc.
• Original Assignee: DENSO Corporation, Nippon Soken, Inc.
• Inventors: Kouda, Shinji, Wakimoto, Toru, Takahashi, Yoshimitsu
• Granted Patent: US 8,368,404 B2
• Time in Patent Office: Days
• US Class Current: 324/76.210
• CPC Class Codes: G01R 31/1272 of cable, line or wire insulation, e.g. using partial discharge measurements locating faults in cables G01R31/083
• CPC Class Codes: G01R 31/34 Testing dynamo-electric machines

Abstract

A discharge amount measuring device includes a power source, first and second sensors, a calibration wire, and a measuring portion. The power source applies a voltage to a coil of a rotational electric machine. The first sensor detects a current flowing through the coil. The calibration wire has an end connected to the coil. The second sensor detects a current flowing through the calibration wire. The measuring portion forms a calibration line based on a first waveform detected by the first sensor and a second waveform detected by the second sensor. The measuring portion calculates a discharge amount based on the calibration line.

Claims

1. A discharge amount measuring device for a rotational electric machine comprising:

a power source to apply a voltage to a coil of the rotational electric machine;

a first current sensor to detect a current flowing through the coil;

a calibration wire having an end connected to the coil;

a second current sensor to detect a current flowing through the calibration wire; and

a measuring portion configured to form a calibration line based on a first current waveform detected by the first current sensor and a second current waveform detected by the second current sensor, wherein

the measuring portion is configured to calculate a discharge amount based on the calibration line.

2. The discharge amount measuring device according to claim 1, wherein

the calibration wire is covered by a first insulating film,

the coil is covered by a second insulation film, and

the first insulating film has a thickness smaller than a thickness of the second insulating film.

3. The discharge amount measuring device according to claim 1, wherein

the calibration wire is arranged to connect the coil and a casing of the rotational electric machine.

4. The discharge amount measuring device according to claim 1, wherein

the coil is one of a plurality of coils, and

the calibration wire is arranged to connect the plurality of coils.

5. The discharge amount measuring device according to claim 4, wherein

the connected coils directly contact with each other.

6. The discharge amount measuring device according to claim 1, further comprising:

a high-pass filter to filter the first current waveform, wherein

the measuring portion forms the calibration line based on a relationship between a peak value or area of the filtered waveform and a discharge amount corresponding to the second current waveform.

7. The discharge amount measuring device according to claim 6, wherein

the measuring portion performs Fourier transform relative to the first current waveform, and

the measuring portion calculates the peak value or area based on a waveform obtained by performing Fourier transform.

8. The discharge amount measuring device according to claim 1, wherein

the measuring portion measures the discharge amount based on a component having a frequency equal to or higher than 100 MHz.

9. A method of measuring a discharge amount for a rotational electric machine comprising:

applying a voltage to a coil mounted to the rotational electric machine;

detecting a current flowing through the coil by a first current sensor;

detecting a current flowing through a calibration wire by a second current sensor, the calibration wire having an end connected to the coil;

forming a calibration line based on a first current waveform detected by the first current sensor and a second current waveform detected by the second current sensor; and

calculating a discharge amount based on the calibration line.